The Yellow River or Huang He (listen) is the second-longest river in Asia, following the Yangtze River, and the sixth-longest river system in the world at the estimated length of 5,464 km (3,395 mi).[1] Originating in the Bayan Har Mountains in Qinghai province of western China, it flows through nine provinces, and it empties into the Bohai Sea near the city of Dongying in Shandong province. The Yellow River basin has an east–west extent of about 1,900 kilometers (1,180 mi) and a north–south extent of about 1,100 km (680 mi). Its total basin area is about 742,443 square kilometers (286,659 sq mi).

Its basin was the birthplace of ancient Chinese civilization, and it was the most prosperous region in early Chinese history. However, because of frequent devastating floods and course changes produced by the continual elevation of the river bed, sometimes above the level of its surrounding farm fields, it also has the names China's Sorrow and Scourge of the Sons of Han.[2]

Early Chinese literature including the Yu Gong or Tribute of Yu dating to the Warring States period (475 – 221 BC) refers to the Yellow River as simply 河 (Old Chinese: *C.gˤaj,[3] modern Chinese (Pinyin) Hé), a character that has come to mean "river" in modern usage. The first appearance of the name 黃河 (Old Chinese: *N-kʷˤaŋ C.gˤaj; Middle Chinese: Huang Ha[3]) is in the Book of Han written during the Eastern Han dynasty about the Western Han dynasty. The adjective "yellow" describes the perennial color of the muddy water in the lower course of the river, which arises from soil (loess) being carried downstream.

The Yellow River Breaches its Course by Ma Yuan (1160–1225), Song Dynasty

The Yellow River is one of several rivers that are essential for China's very existence. At the same time, however, it has been responsible for several deadly floods, including the only natural disasters in recorded history to have killed more than a million people. The deadliest was a 1332–33 flood that killed 7 million people. Close behind is the 1887 flood, which killed anywhere from 900,000 to 2 million people, and a 1931 flood (part of a massive number of floods that year) that killed 1–4 million people.[7]

The cause of the floods is the large amount of fine-grained loess carried by the river from the Loess Plateau, which is continuously deposited along the bottom of its channel. The sedimentation causes natural dams to slowly accumulate. These subaqueous dams were unpredictable and generally undetectable. Eventually, the enormous amount of water has to find a new way to the sea, forcing it to take the path of least resistance. When this happens, it bursts out across the flat North China Plain, sometimes taking a new channel and inundating any farmland, cities or towns in its path. The traditional Chinese response of building higher and higher levees along the banks sometimes also contributed to the severity of the floods: When flood water did break through the levees, it could no longer drain back into the river bed as it would after a normal flood as the river bed was sometimes now higher than the surrounding countryside. These changes could cause the river's mouth to shift as much as 480 km (300 mi), sometimes reaching the ocean to the north of Shandong Peninsula and sometimes to the south.[8]

Another historical source of devastating floods is the collapse of upstream ice dams in Inner Mongolia with an accompanying sudden release of vast quantities of impounded water. There have been 11 such major floods in the past century, each causing tremendous loss of life and property. Nowadays, explosives dropped from aircraft are used to break the ice dams before they become dangerous.[9]

Before modern dams came to China, the Yellow River was extremely prone to flooding. In the 2,540 years from 595 BCE to 1946 CE, the Yellow River has been reckoned to have flooded 1,593 times, shifting its course 26 times noticeably and nine times severely.[10] These floods include some of the deadliest natural disasters ever recorded. Before modern disaster management, when floods occurred, some of the population might initially die from drowning but then many more would suffer from the ensuing famine and spread of diseases.[11]

The Yellow River as depicted in a Qing dynasty illustrated map (sections)

A map of China depicting the Yellow River's path (shown in blue in the upper half of the map) in the early 19th century.

Historical documents from the Spring and Autumn period[12] and Qin Dynasty[13] indicate that the Yellow River at that time flowed considerably north of its present course. These accounts show that after the river passed Luoyang, it flowed along the border between Shanxi and Henan Provinces, then continued along the border between Hebei and Shandong before emptying into Bohai Bay near present-day Tianjin. Another outlet followed essentially the present course.[10]

The river left these paths in 602 BC[12] and shifted completely south of the Shandong Peninsula.[10] Sabotage of dikes, canals, and reservoirs and deliberate flooding of rival states became a standard military tactic during the Warring States period.[14] As the Yellow River valley was the major entryway to the Guanzhong area and the state of Qin from the North China Plain, Qin heavily fortified the Hangu Pass; it saw numerous battles and was also an important chokepoint protecting the Han capitals of Chang'an and Luoyang. Major flooding in AD 11 is credited with the downfall of the short-lived Xin dynasty, and another flood in AD 70 returned the river north of Shandong on essentially its present course.[10]

From around the beginning of the 3rd century, the importance of the Hangu Pass was reduced, with the major fortifications and military bases moved upriver to Tongguan. In AD 923, the desperate Later Liang general Duan Ning again broke the dikes, flooding 1,000 square miles (2,600 km2) in a failed attempt to protect his realm's capital from the Later Tang. A similar proposal from the Song engineer Li Chun concerning flooding the lower reaches of the river to protect the central plains from the Khitai was overruled in 1020: the Treaty of Shanyuan between the two states had expressly forbidden the Song from establishing new moats or changing river courses.[15]

Breaches occurred regardless: one at Henglong in 1034 divided the course in three and repeatedly flooded the northern regions of Dezhou and Bozhou.[15] The Song worked for five years futilely attempting to restore the previous course – using over 35,000 employees, 100,000 conscripts, and 220,000 tons of wood and bamboo in a single year[15] – before abandoning the project in 1041. The more sluggish river then occasioned a breach at Shanghu that sent the main outlet north towards Tianjin in 1048[10] and by 1194 blocked the mouth of the Huai River.[16] The buildup of silt deposits was such that even after the Yellow River later shifted its course, the Huai could no longer flow along its historic course, but instead, its water pools into Hongze Lake and then runs southward toward the Yangtze River.[citation needed]

A flood in 1344 returned the Yellow River south of Shandong. The Yuan dynasty was waning, and the emperor forced enormous teams to build new embankments for the river. The terrible conditions helped to fuel rebellions that led to the founding of the Ming dynasty.[8] The course changed again in 1391 when the river flooded from Kaifeng to Fengyang in Anhui. It was finally stabilized by the eunuch Li Xing during the public works projects following the 1494 flood.[17]

The river flooded many times in the 16th century, including in 1526, 1534, 1558, and 1587. Each flood affected the river's lower course.[17]

The 1642 flood was man-made, caused by the attempt of the Ming governor of Kaifeng to use the river to destroy the peasant rebels under Li Zicheng who had been besieging the city for the past six months.[18] He directed his men to break the dikes in an attempt to flood the rebels, but destroyed his own city instead: the flood and the ensuing famine and plague are estimated to have killed 300,000 of the city's previous population of 378,000.[19] The once-prosperous city was nearly abandoned until its rebuilding under the Kangxi Emperor in the Qing Dynasty.

The 1931 flood killed an estimated 1,000,000 to 4,000,000,[20] and is the worst natural disaster recorded (excluding famines and epidemics).

On 9 June 1938, during the Second Sino-Japanese War, Nationalist troops under Chiang Kai-shek broke the levees holding back the river near the village of Huayuankou in Henan, causing what has been called by Canadian historian, Diana Lary, a "war-induced natural disaster". The goal of the operation was to stop the advancing Japanese troops by following a strategy of "using water as a substitute for soldiers" (yishui daibing). The 1938 flood of an area covering 54,000 km2 (20,800 sq mi) took some 500,000 to 900,000 Chinese lives, along with an unknown number of Japanese soldiers. The flood prevented the Japanese Army from taking Zhengzhou, on the southern bank of the Yellow River, but did not stop them from reaching their goal of capturing Wuhan, which was the temporary seat of the Chinese government and straddles the Yangtze River.[22]

The upper reaches of the Yellow River constitute a segment starting from its source in the Bayan Har Mountains and ending at Hekou Town (Togtoh County), Inner Mongolia just before it turns sharply to the south. This segment has a total length of 3,472 kilometers (2,157 mi) and total basin area of 386,000 square kilometers (149,000 sq mi), 51.4% of the total basin area. Along this length, the elevation of the Yellow River drops 3,496 meters (11,470 ft), with an average grade of 0.10%.

The source section flows mainly through pastures, swamps, and knolls between the Bayan Har Mountains, and the Anemaqen (Amne Machin) Mountains. The river water is clear and flows steadily. Crystal clear lakes are characteristic of this section. The two main lakes along this section are Lake Zhaling (扎陵湖) and Lake Eling (鄂陵湖), with capacities of 4.7 billion and 10.8 billion m³ (166 and 381 billion ft3), respectively. At elevations over 4,290 m (14,070 ft)) above sea level they are the two largest plateau freshwater lakes nationwide. A significant amount of land in the Yellow River's source area has been designated as the Sanjiangyuan ("'Three Rivers' Sources") National Nature Reserve, to protect the source region of the Yellow River, the Yangtze, and the Mekong.

The valley section stretches from Longyang Gorge in Qinghai to Qingtong Gorge in Gansu. Steep cliffs line both sides of the river. The water bed is narrow and the average drop is large, so the flow in this section is extremely turbulent and fast. There are 20 gorges in this section, the most famous of these being the Longyang, Jishi, Liujia, Bapan, and Qingtong gorges. The flow conditions in this section makes it the best location for hydroelectric plants.

After emerging from the Qingtong Gorge, the river comes into a section of vast alluvial plains, the Yinchuan Plain and Hetao Plain. In this section, the regions along the river are mostly deserts and grasslands, with very few tributaries. The flow is slow. The Hetao Plain has a length of 900 km (560 mi) and width of 30 to 50 km (19 to 31 mi). It is historically the most important irrigation plain along the Yellow River.

The Ordos Loop formed by an enormous twist of the Yellow River, beginning at Zhongning County in Ningxia and ending with a drastic eastward turn at its confluence with the Wei at Tongguan in Shaanxi. However, the official division for the middle reaches of the river run from Hekou in Togtoh County, Inner Mongolia, to Zhengzhou, Henan. The middle reaches are 1,206 km (749 mi) long, with a basin area of 344,000 square kilometers (133,000 sq mi), 45.7% of the total, with a total elevation drop of 890 m (2,920 ft), an average drop of 0.074%. There are 30 large tributaries along the middle reaches, and the water flow is increased by 43.5% on this stage. The middle reaches contribute 92% of the river's silts.

The middle stream of the Yellow River passes through the Loess Plateau, where substantial erosion takes place. The large amount of mud and sand discharged into the river makes the Yellow River the most sediment-laden river in the world. The highest recorded annual level of silts discharged into the Yellow River is 3.91 billion tons in 1933. The highest silt concentration level was recorded in 1977 at 920 kg/m³ (57.4 lb/ft3). These sediments later deposit in the slower lower reaches of the river, elevating the river bed and creating the famous "river above ground". From Hekou to Yumenkou, the river passes through the longest series of continuous valleys on its main course, collectively called the Jinshan Valley. The abundant hydrodynamic resources stored in this section make it the second most suitable area to build hydroelectric power plants. The famous Hukou Waterfall is in the lower part of this valley on the border of Shanxi and Shaanxi.

In the lower reaches, from Zhengzhou, Henan to its mouth, a distance of 786 km (488 mi), the river is confined to a levee-lined course as it flows to the northeast across the North China Plain before emptying into the Bohai Sea. The basin area in this stage is only 23,000 square kilometers (8,900 sq mi), a mere 3% of the total, because few tributaries add to the flow in this stage; nearly all rivers to the south drain into the Huai River, whereas those to the north drain into the Hai River. The total drop in elevation of the lower reaches is 93.6 m (307 ft), with an average grade of 0.012%.

The silts received from the middle reaches form sediments here, elevating the river bed. During 2,000 years of levee construction, excessive sediment deposits have raised the riverbed several meters above the surrounding ground.[dubious– discuss]

At Kaifeng, Henan, the Yellow River is 10 meters (33 ft) above the ground level.[25]

Expansion of the Yellow River Delta from 1989 to 2009 in five year intervals.

The Yellow River is notable for the large amount of silt it carries—1.6 billion tons annually at the point where it descends from the Loess Plateau. If it is running to the sea with sufficient volume, 1.4 billion tons are carried to the sea annually.[citation needed] One estimate gives 34 kilograms of silt per cubic meter as opposed to 10 for the Colorado and 1 for the Nile.[26]

Its average discharge is said to be 2,110 cubic meters per second (32,000 for the Yangtze), with a maximum of 25,000 and minimum of 245. However, since 1972, it often runs dry before it reaches the sea. The low volume is due to increased agricultural irrigation, increased by a factor of five since 1950. Water diverted from the river as of 1999 served 140 million people and irrigated 74,000 km² (48,572 mi²) of land.[23] The Yellow River delta totals 8,000 square kilometers (3,090 mi²). However, with the decrease in silt reaching the sea, it has been reported to be shrinking slightly each year since 1996 through erosion.[27]

The highest volume occurs during the rainy season from July to October, when 60% of the annual volume of the river flows. Maximum demand for irrigation is needed between March and June. In order to capture excess water for use when needed and for flood control and electricity generation, several dams have been built, but their expected life is limited due to the high silt load. A proposed South–North Water Transfer Project involves several schemes to divert water from the Yangtze River: one in the western headwaters of the rivers where they are closest to one another, another from the upper reaches of the Han River, and a third using the route of the old Grand Canal.[citation needed]

Due to its heavy load of silt the Yellow River is a depositing stream – that is, it deposits part of its carried burden of soil in its bed in stretches where it is flowing slowly. These deposits elevate the riverbed which flows between natural levees in its lower reaches. Should a flood occur, the river may break out of the levees into the surrounding lower flood plain and take a new channel. Historically this has occurred about once every hundred years. In modern times, considerable effort has been made to strengthen levees and control floods.[citation needed]

The Yellow River is generally less suitable for aquaculture than the rivers of central and southern China, such as the Yangtze or the Pearl River, but aquaculture is also practiced in some areas along the Yellow River. An important aquaculture area is the riverside plain in Xingyang City, upstream from Zhengzhou. Since the development of fish ponds started in Xingyang's riverside Wangcun Town in 1986, the pond systems in Wangcun have grown to the total size of 15,000 mu (10 km2), making the town the largest aquaculture center in North China.[32]

A variety of the Chinese softshell turtle popular with China's gourmets is called the Yellow River Turtle (黄河鳖). Nowadays most of the Yellow River Turtles eaten in China's restaurants comes from turtle farms, which may or may not be near the Yellow River. In 2007, construction started in Wangcun on a large farm for raising this turtle variety. With the capacity for raising 5 million turtles a year, the facility was expected to become Henan's largest farm of this kind.[33]

On 25 November 2008, Tania Branigan of The Guardian filed a report "China's Mother River: the Yellow River", claiming that severe pollution has made one-third of China's Yellow River unusable even for agricultural or industrial use, due to factory discharges and sewage from fast-expanding cities.[34] The Yellow River Conservancy Commission had surveyed more than 8,384 mi (13,493 km) of the river in 2007 and said 33.8% of the river system registered worse than "level five" according to the criteria used by the UN Environment Program.[dubious– discuss] Level five is unfit for drinking, aquaculture, industrial use, or even agriculture. The report said waste and sewage discharged into the system last year totaled 4.29b tons. Industry and manufacturing made up 70% of the discharge into the river with households accounting for 23% and just over 6% coming from other sources.[which?]

In ancient times, it was believed that the Yellow River flowed from Heaven as a continuation of the Milky Way. In a Chinese legend, Zhang Qian is said to have been commissioned to find the source of the Yellow River. After sailing up-river for many days, he saw a girl spinning and a cow herd. Upon asking the girl where he was, she presented him with her shuttle with instructions to show it to the astrologer Yen Chün-p'ing. When he returned, the astrologer recognized it as the shuttle of the Weaving Girl (Vega), and, moreover, said that at the time Zhang received the shuttle, he had seen a wandering star interpose itself between the Weaving Girl and the cow herd (Altair).[35]

The provinces of Hebei and Henan derive their names from the Yellow River. Their names mean, respectively, "North of the River" and "South of the River".

Sometimes the Yellow River is poetically called the "Muddy Flow" (simplified Chinese: 浊流; traditional Chinese: 濁流; pinyin: ZhuóLiú). The Chinese idiom "when the Yellow River flows clear" is used to refer to an event that will never happen and is similar to the English expression "when pigs fly".

"The Yellow River running clear" was reported as a good omen during the reign of the Yongle Emperor, along with the appearance of such auspicious legendary beasts as qilin (an African giraffe brought to China by a Bengal embassy aboard Zheng He's ships in 1414) and zouyu (not positively identified) and other strange natural phenomena.[37]